The use of fiber reinforced resin matrix composite laminates has been widely accepted, particularly within the aerospace and automotive industries, due to the high specific strength and stiffness of such materials. The strong interest in applying composite laminates is motivated primarily by the weight reduction and the associated cost and performance benefits that typically arise when such materials are used to replace metals. A major obstacle to expansion of the range of applicability of composite laminates has been the temperature limitations of the resin matrix materials.
Resin matrix materials with increased temperature resistance, for example, bismaleimide and polyimide resins as well as some epoxy formulations, have been developed. A serious detriment associated with the use of these advanced resin matrix materials to produce high temperature composite laminates is the problem of microcracking. Microcracking is the formation of a multitude of small fractures in the resin matrix of a composite laminate. The fractures typically develop under two sets of circumstances, either as the laminate is cooled to ambient temperature following an elevated temperature resin cure cycle or as the laminate undergoes temperature cycling during use. High temperature composite laminates are particularly susceptible to microcracking due to the brittleness that characterizes the high temperature resistant resin matrix materials and extreme temperatures enountered during fabrication and use.
What is needed in this art is microcrack resistant fiber reinforced resin matrix composite laminates for elevated temperature applications.